Gasoline fuel composition



United States Patent 3,226,209 GASOLINE FUEL COMPOSITION Shirl E. Cook and Hymin Shapiro, Baton Rouge, La., assignors to Ethyl Corporation, New York, N.Y., a corporation of Virginia No Drawing. Filed Apr. 13, 1964, Ser. No. 359,471 6 Claims. (Cl. 4469) This application is a continuation-in-part of application Serial No. 70,411, filed November 11, 1960, now abandoned.

This invention relates to, and has as its chief object, the provision of self-scavenging leaded gasolines having enhanced engine inductibility characteristics.

Ever since the early 1920s the art, including continuous commercial practice, has considered the use with lead alkyl antiknocks of halogen scavengers to be essential. Tremendous efforts have gone into the development of more effective halogen scavengers and more ideal concentrations and proportions thereof. Some of the great improvements resulting from these efforts are described in US. Patents 2,364,921; 2,398,281; 2,479,900; 2,479,- 901; 2,479,902; 2,479,903; 2,496,983; 2,661,379; 2,822,- 252; 2,849,302; 2,849,303; 2,849,304; 2,844,905; and 2,869,993.

Recently other types of lead scavengers have been proposed and evaluated. These include certain phosphorous compounds (US. 2,765,220; 2,828,195; 2,841,- 480; 2,843,465); sulfur compounds (U.S. 2,557,019); arsenic, antimony and bismuth compounds (US. 2,750,- 267; 2,819,156); tin compounds (US. 2,586,660); and so forth. One or two of these types of scavengers have enjoyed commercial usage as supplements to the commercially long-used halohydrocarbon scavengers. However, none of these newer scavengers has ever been cornmercially used in the absence of a halogen scavenger.

Still more recently a completely new approach to the scavenging problem has been disclosed by our colleagues. Their discovery, a radical departure from all previous concepts and practice, is a self-scavenging motor fuel composition for spark ignition internal combustion engines which essentially consists of a halogen scavengerfree motor gasoline base stock and an alkyllead antiknock agent, the base stock being characterized by having a content of aromatic gasoline hydrocarbons ranging from about 10 to about 60 volume percent based on the whole fuel, The balance of the base stock is composed of saturates, olefins, or both. Such fuel compositions have been found to provide distinct and very important improvements in engine operation, especially from the standpoint of improved exhaust valve durability. The economic advantages of this pioneering discovery will also be apparent.

The foregoing discovery is revolutionary. If put into commercial practice it would give rise for the first time to the sale in large-sized quantities of tetraalkyllead compounds undiluted by their conventional halide scavenger complement.

According to prior commercial practice, about 35 percent by weight of the commercial antiknock fluid compositions has been composed of either ethylene dibromide or a mixture of ethylene dibromide and ethylene dichloride as the scavenger. Although designed primarily to overcome certain engine problems, these scavengers have conferred upon the resultant antiknock fluid composition a very substantial degree of thermal stability. Consequently the elimination of such substantial amounts of scavenger components from the antiknock mixture results in the elimination of the thermal stability protection heretofore afforded by the scavenger. In fact, the resultant pure alkyllead compound is a liquid monopropellant-that is, it can undergo a spontaneous and highly exothermic decomposition, liberating a large volume of hot gas. Hence when a critical mass of alkyllead compound under partial confinement is brought up to a sufficient temperature, it will then heat itself up and explode.

The problem of effectively inhibiting the above-described thermal decomposition is critical to the commercialization the new antiknock additive because in commercial use the additive would be shipped and stored in much the same way as present scavenger-containing alkyllead antiknock fluids. Unless the new antiknock additives were properly stabilized against thermal decomposition and unless it had essentially the same thermal stability as the presently-sold antiknock fluids, the consequences could be disastrous.

In our prior, co-pending application Serial Number 20,010, filed April 5, 1960, now Patent No. 3,03 8,961-all disclosure of which is incorporated herein by the foregoing referencewe have described a very effective means by which this thermal stability problem is overcome. This is accomplished by providing an alkyllead compound normally susceptible to rapid thermal decomposition at elevated temperatures (eg, 195 C.) having admixed therewith a plurality of different fused ring aromatic hydrocarbons in amount sufiicient to inhibit such decomiposition, said hydrocarbons having boiling points at atmospheric pressure (or extrapolated thereto) of at least about 180 C. and containing up to about 20 carbon atoms in the molecule.

Unfortunately, however, the use of the above thermally stabilized scavenger-free alkyllead antiknock compositions in gasoline often causes the formation of unduly excessive amounts of intake manifold deposits. Experiments have shown that these excessive deposits result from the presence in the fuel of the above-described fused ring aromatic hydrocarbon mixtures. Since these mixtures are much higher boiling than the gasoline hydrocarbons, they accumulate in the manifold and through exposure to a combination of heat and air, they are quickly converted to substantial quantities of pentane-insoluble deposits. These deposits adhere tenaciously to the critical inner surfaces of the intake manifolds and have a strong tendency to impair proper engine operation.

As an example of the foregoing undesirable behavior, standard engine tests have shown that the presence in gasoline of a typical fused ring aromatic hydrocarbon thermal stabilizer mixture caused the formation of about 400 percent as much pentane-insoluble manifold deposits as were caused in the absence of this thermal stabilizer component. Therefore, although the thermal stabilizer mixtures are exceedingly effective in overcoming the thermal instability problem, their use in the fuel has given rise to this induction system deposit problem.

The fused ring aromatic hydrocarbon thermal stabilizer materials have been found to be troublesome in causing an increase in total manifold deposits as well as in pentane-insoluble deposits. The following test illustrates this.

This test is designed to study deposits of the type formed on the intake manifold or intake-valve when different additives or fuels are used. The test apparatus consists of two portions. (1) A glass tube to simulate a manifold. (2) A baffled-tube to simulate an intake-valve.

The manifold is a glass jacketed l x 50 cm. tube maintained at a given temperature by refluxing a suitable vapor around the tube. Fuel is injected into the air stream just before it enters the manifold. The air and fuel are metered through flowmeters and controlled by stainless steel needle valves. The baffled-tube portion of the apparatus consists of a stainless steel outer tube 7% inches long and inch in diameter. It contains a stainless steel inner tube inch in diameter closed at both ends. The inner tube has three inch diameter baffles equally spaced. The baflie-tube is housed in a heater. A thermocouple projects through the heater so that the junction rests against the tube. This enables measurement of the skin temperature at the center of the tube. The bafiie-tube portion of the apparatus is connected to the exhaust end of the manifold. Both the manifold and baffle-tube are in a horizontal position.

A 500 ml. sample of fuel is aspirated at 14:1 air: fuel ratio into the above apparatus at a fuel flow rate of 4 ml. per minute. After the fuel supply is exhausted air is passed through for one-half hour to cool the system. The apparatus is then dismantled and the amount of isopentane and tri-solvent (acetone, benzene, methanol) soluble deposits in the manifold determined. The bafiietube is Weighed to determine the deposits collected. Manifold temperature during the test run is maintained at 127 C. by refluxing m-xylene and preheating the air. The baffie tube is heated to 288 C. by controlling the heater with a Variac. The air flow rate, fuel flow rate, input air temperature and manifold temperature are all controlled to within about 1 percent of the stated values.

In this test a sample of gasoline containing 3.17 grams per gallon of lead as tetraethyllead (no halogen scavenger present), but not containing any fused ring aromatic hydrocarbon thermal stabilizer mixture gave a total deposit weight of 14.1 milligrams. When the same fuel, identical in all respects except that it additionally contained 0.317 part of a typical fused ring aromatic hydrocarbon thermal stabilizer mixture of the type described herein was put to the same test under identical conditions, the total deposit weight was 26 milligrams. Moreover, the fuel containing the thermal stabilizer caused higher deposit weights both of the pentane-soluble and pentane-insoluble type than did the leaded base fuel.

Accordingly, a specific object of this invention is to overcome the foregoing induction system deposit problem. Another object is to provide halogen scavenger-free leaded gasoline compositions containing the above-defined thermal stabilizer mixtures which fuel compositions are made technologically superior from the induction system cleanliness standpoint through the association therewith of an efficient induction system cleanliness additive. Another important object will become apparent from the following description.

We have now found that the above and other objects of this invention are accomplished by employing certain triaryl phosphates in scavenger-free leaded gasolines containing the fused ring aromatic hydrocarbon thermal stabilizer mixtures. Very surprisingly the triaryl phosphates cause very substantial reductions in the amount of pentane-insoluble deposits formed in the intake manifold.

The particular phosphate esters used according to this invention are those in which the aryl groups are selected from the group consisting of phenyl, cresyl and xylyl. Hence, these phosphate esters include triphenyl phosphate, tricresyl phosphate, trixylyl phosphate; as well as various mixed phosphate esters such as cresyl diphenyl phosphate, phenyl dicresyl phosphate, dicresyl xylyl phosphate, and the like.

Accordingly, we provide pursuant to this invention:

A halogen scavenger-free leaded gasoline composition of enhanced engine inductibility characteristics essentially consisting of: gasoline; an alkyllead antiknock agent present in the gasoline in amount equivalent from about 1 to about 5 grams of elemental lead per gallon; a mixture of different fused ring aromatic hydrocarbons having boiling points at atmospheric pressure of at least about 180 C. and containing up to about 20 carbon atoms in the molecule, said mixture being present in amount equivalent to from about 5 to about 30 parts by Weight per each 100 parts by weight of said agent; and a triaryl phosphate ester in which the aryl groups are selected from the group consisting of phenyl, tolyl, and xylyl, the phosphorus content of the composition ranging from about 0.2 to about 0.6 theory based on the lead content of the composition.

The suitability of our compositions, in terms of induction system deposit reduction, pertains without regard to the hydrocarbon composition of the base gasoline employed. Good results are obtained, for example, with fuels containing no aromatics and fuels containing substantial amounts of aromatics, such as 60 percent, as well as fuels intermediate in aromatic content.

In terms, however, of antiknock effectiveness of the halogen scavenger-free alkyllead antiknock agents, and in particular of their self-scavenging ability, it is preferable, as explained above, to employ in the present compositions, base gasolines which are characterized by having a content of aromatic gasoline hydrocarbon ranging from about 10 to about 60 volume percent based on the whole fuel.

By definition, a theory of phosphorus is that quantity theoretically required to react with the lead present to form lead orthophosphate, Pb (PO Hence, one theory of phosphorus is equivalent to a phosphorus-tolead atom ratio of 2:3.

Although this invention is effectively practiced by using any of the well known alkyllead antiknock agents, such as those containing from 4 to about 20 carbon atoms in the molecule, particularly good results are achieved with tetramethyllead, ethyl trimethyl lead, diethyl dimethyl lead, triethylmethyl lead, tetraethyllead, or mixtures thereof. Accordingly, the use of these particular alkyllead antiknoek agents is preferred.

Another preferred embodiment of this invention involves the use as the gasoline component of one containing from about 20 to about 55 volume percent of aromatic gasoline hydrocarbons, again the balance being composed of saturates, olefins, or both.

Particularly good results have been achieved by using about 0.4 theory of phosphorus as tricresyl phosphate in association with a fused ring aromatic hydrocarbon thermal stabilizer mixture which includes methyl naphthalenes and dimethyl naplhthalenes. Hence, this forms still another preferred embodiment of this invention.

That the above phosphate esters cause substantial reductions in intake manifold deposit formation is a singularly unexpected result. All of these triaryl phosphates have very high boiling points and are thus classifiable as essentially non-volatile substances. For example, triphenyl phosphate is reported to have a bOllling point of 245 C. at 1 1 mm. of mercury pressure, whereas tri-m-cresyl phosphate reportedly boils at 273 275 C. at 17 mm. of mercury pressure. Similarly, trio-cresyl phosphate is indicated in the literature to boil at 410 C. with slight decomposition.

As might be expected from the relative non-volatility of the above phosphate esters, these materials when used in halogen scavenger-free leaded gasoline in the absence of the above thermal stabilizers have been found to cause significant increases in the amount of intake manifold deposits. Thus in one series of experiments in which tricresyl phosphate Was used in a commercially available gasoline containing 3 ml. per gallon of pure tetraethyllead (i.e., no halogen scavenger was present), it was found that the amount of pentane-insoluble intake manifold deposits was increased by as much as 30 percent as compared with the corresponding phosphorus-free leaded fuel.

Thus, the present invention can be viewed as the addition of an involatile phosphate esterwhich itself normally tends to increase induction system deposit formation-to a fuel composition containing an involatile aromatic hydrocarbon mixture which likewise markedly increases induction system deposit formation. And yet when used conjointly, these involatile substances beneficially coact with each other in such a way as to result in a reduction of the induction system deposit formed as compared with the deposit formation subsisting in the absence of the phosphate ingredient. There is presently no satisfactory explanation for this beneficial behavior.

This invention will be further apparent from the following specific examples.

EXAMPLE I Blended with a motor gasoline base stock containing by volume 40.2 percent of aromatics, 5.6 percent of olefins, and 54.2 percent of saturates, to a concentration of 2.5 grams of lead per gallon is a tetraethyll-ead antiknock fluid composition. This composition consists of tetraethyllead and a commercially available mixture of fused ring aromatic hydrocarbons having maximum viscosity of 500 Saybolt Universal Seconds (SSU) at 75 F. and of 100 SSU at 212 F. and containing fused ring aromatic hydrocarbons including naphthalene, alkyl naphthalenes, and 1, 2, 3, 4-tetrahydronaphthale-ne. In this antiknock composition, there are 5 parts by weight of the hydrocarbon mixture per each 100 parts by weight of the tetraethyllead. Then triphenyl phosphate is blended with this motor fuel mixture to a concentration of 0.2 theory of phosphorus.

EXAMPLE II In this instance, the gasoline base stock is composed by volume of 35.2 percent of aromatics, 25.0 percent of olefins, and 39.8 percent of saturates. Blended to a concentration of 4.2 grams of lead per gallon with the foregoing gasoline is an antiknock fluid composition consisting of equimolar quantities of tetraethyllead and a commercially available mixture of fused ring aromatic hydrocarbons having an initial boiling point of 232 C., a 50 percent point of 247 C., and a final boiling point of 279 C. This mixture, which was shown. by instrumental chemical anaiysis to contain, inter alia, significant quantities of Z-methyl naphthalene and various dimethyl naphtharenes, principally 1,3-dimethyl naphthalene, 1,4- dimethyl naphthalene, and 1,6-dimethyl naphthalene. This mixture is associated with the above alkyllead compounds in amount such that there are 20 parts thereof per each 100 parts by weight of the alkyllead compounds. Thereupon, trixylylphos-phate is blended with this motor fuel composition in amount such that there is 0.5 theory of phosphorus present.

EXAMPLE III Used in this example is a motor fuel composed by volume of 42.5 percent aromatics, 10.8 percent olefins, and 46.7 percent saturates. Blended therewith to a concentration of 1 gram of lead per gallon is an antiknock fluid formulation consisting of tetrabutyllead, anthracene, and l-methyl naphthalene, this formulation containing 5 parts by weight of anthracene and 5 parts by weight of l-methyl naphthalene per each 100 parts by weight of the tetrabutyilead. Then, cresyl diphenyl phosphate is admixed with the fuel composition to a concentration of 0.3 theory of phosphorus.

EXAMPLE IV The base fuel used in this instance contains 12 volume percent aromatics, 8 volume percent olefins, and 80 volume percent saturates, Incorporated into this fuel to a concentration of 5 grams of lead per gallon is an antiknock fluid composition consisting of tetramethyllead, anthracene, 1,2,3,4-tetrahydronaphthalene, and 2-methyl naphthalene. In this antiknock fluid composition, there are 1 part by weight of anthracene, 2 parts by Weight of the tetrahydronaphthalene, and 2 parts by weight of the methyl naphthalene per each 100 parts by weight of the tetramethyllead. Thereupon, a mixture of cresyl diphenyl phosphate and tricresyl phosphate (25.75 mole percent, respectively) is blended with the fuel to a concentration of 0.6 theory of phosphorus.

6 EXAMPLE v Conjointly mixed with a portion of trimethylethyllead are l-ethyl naphthalene, phenanthrene, crysene and 1,4- dimethyl naphthalene so that these hydrocarbons are present in amount corresponding in parts by weight to 5, 0.5, 0.5, and 3, respectively, per each 100 parts by weight of the trimethylethyllead. With another portion of the trimethylethyllead are blended a benzene solution of 9-phenyl anthracene (such that the concentration of the latter corresponds to 1 part by weight based on 100 parts by weight of the lead compound), l-benzyl naphthalene (0.25 part by weight per each 100 parts by weight of the lead compound), fiuorene (0.5 part by weight per each 100 parts by weight of the lead compound), and pyrene (0.05 part by weight per each 100 parts by weight of the lead compound). Each of these antiknock fluid compositions is blended to a concentration of 3 grams of lead per gallon with a portion of a gasoline base stock containing 23.7 volume percent aromatics, 15.7 volume percent olefins, and 57.0 volume percent saturates. Thereupon, triphenyl phosphate is dissolved in the gasoline containing the first-named antiknock fluid composition to a concentration of 0.25 theory of phosphorus. With the secondnamed fuel composition, diphenyl cresyl phosphate is blended to a concentration of 0.4 theory of hosphorus.

EXAMPLE VI The composition of Example IV is duplicated except that the base fuel is an alkylate gasoline consisting of substantially 100 percent saturates.

As an illustration of the striking advantageous results achieved from this invention a series of standard heated manifold engine tests were conducted, the test technique in question being one used widely in the art as an effective measure of the effect of fuel components and fuel additives on intake manifold deposit formation. In all of these tests a modern automotive gasoline base stock containing approximately percent by volume of aromatic gasoline hydrocarbons was used. Likewise, in all instances this base fuel contained 3.18 grams of lead per gallon as tetraethyllead. No halogen scavenger was associated there with in any of the tests.

Base line tests were run comparing the additive-free leaded gasoline base stock with another portion of the same fuel with which had been blended tricresyl phosphate at a concentration of 0.4 theory of phosphorus. These base line tests established that the amount of pentane insolubles formed in the intake manifold during the stand ard test period were increased by the presence of the trh cresyl phosphate by 30 percent. Accordingly, these demonstrations established the fact that the triaryl phosphates when used as the sole supplementary additive have a strong tendency to increase the manifold deposition.

On completion of the above base line tests another pair of identical tests were carried out, the sole variable being in the supplementary additive complement used in the above leaded fuel. Thus in one test the above leaded gasoline contained in addition to the tetraethyllead a commercially available mixture of fused ring aromatic hydrocarbons which were shown by infrared and ultraviolet analyses to contain significant quantity of dimethyl naphthalene isomers as well as some highly polynuclear aromatic components. This hydrocarbon mixture has the following distillation profile:

Distillation: C.

Initial 254 10 percent 267 percent 282 percent 307 Final 323 This hydrocarbon mixture was present in the fuel composition in amount such that there were 15 parts by weight thereof per each parts by weight of tetraethyllead.

In the other test a portion of the leaded fuel just described also contained tricresyl phosphate at a concentration of 0.4 theory of phosphorus. Each of these two fuels was then subjected to the standard heated manifold test procedure for the same test period. The results are shown in the following table:

Efiect of additives on intake manifold deposits Pent-ane insolubles Additive compositions: in manifold, rng.

Aromatic hydrocarbon mixture 505.8 Aromatic hydrocarbon mixture plus tricresyl phosphate 306.3

It will be seen from the above data that the presence in the fuel composition of the tricresyl phosphate causes a sharp reduction in the amount of pentane insolubles that were formed during the test. As a matter of fact the amount of such insolubles was reduced by approximately 40 percent.

When the other compositions of this invention are subjected to the same test procedure, essentially identical results are obtained.

A wide variety of fused ring aromatic hydrocarbon mixtures are available for use in accordance with this invention. For further details concerning the nature of these materials and the manner by which they are used, reference should be had to our prior co-pending application, Serial No. 20,010, referred to above.

As pointed out above, a preferred embodiment of this invention is one in which the base stock contains from about to about 60 volume percent of aromatic gasoline hydrocarbons. An excellent source of these aromatic hydrocarbons is catalytic reforming. The remainder of the base fuel is composed of saturates, olefins, or both. The olefins are generally formed by using such procedures as thermal cracking, catalytic cracking and polymerization. Dehydrogenation of paraffins to olefins can supplement the gaseous olefins occurring in the refinery to produce feed material for either polymerization or alkylation processes. The saturated gasoline components comprise paraffins and naphthenes. These saturates are obtained from (1) virgin gasoline by distillation (straight run gasoline), (2) alkylation processes (alkylates) and (3) isomerization procedures (conversion of normal paraffins to branched chain paraffins of greater octane quality). Saturated gasoline components also occur in so-called natural gasoline. In addition to the foregoing, thermally cracked stocks, catalytically cracked stocks and catalytic reformates contain saturated components.

The above classification of gasoline components into aromatics, olefins and saturates is well recognized in the art. Procedures for analyzing gasolines and gasoline components for hydrocarbon composition have long been known and used. Commonly used today is the FIA analytical method involving fluorescent indicator absorption techniques. These are based on selective absorption of gasoline components on an activated silica gel column, the components being concentrated by hydrocarbon type in different parts of the column. Special fluorescent dyes are added to the test sample and are also selectively separated with the sample fractions to make the boundaries of the aromatics, olefins and saturates clearly visible under ultraviolet light. Further details concerning this method can be found in ASTM Standards on Petroleum Products and Lubricants, November 1957 Edition, under ASTM Test Designation D1319-56T.

The motor gasoline base stocks used in formulating the improved fuels of this invention generally have initial boiling points ranging from about 80 to about 105 F. and final boiling points ranging from about 380 to about 430 F. as measuring by the standard ASTM distillation procedure (ASTM D-86). Intermediate gasoline fractions boil away at temperatures within these extremes.

Methods for the preparation of alkyllead antiknock agents used in the practice of this invention are well known 8. and reported in the literature. For example, recourse may be had to the alkyllead manufacturing processes described in US. Patents 2,414,058; 2,535,190-193; 2,535,235-237; 2,558,207; 2,562,856; 2,574,759; 2,575,323; 2,591,509; 2,594,183; 2,594,225; 2,621,199; 2,621,200; 2,635,105; 2,635,107; 2,660,591-596; 2,688,628; 2,727,053; 2,859,- 225-226; 2,859,228-232; etc. Generally speaking, the tetraalkyllead antiknock agents used in the fuels of this invention can contain from 4 to about 20 carbon atoms in the molecule, although on a cost-effectiveness basis, tetraethyllead is preferred.

Methods for the preparation of the phospate additives used according to this invention are likewise well known and reported in the literature. These methods generally involve reaction between phos'phoryl chloride and an appropriate phenolic compound (i.e. phenol, cresol, xylenol, or mixtures of two or more of these). Three moles of the phenolic compound react with each mole of the phosphoryl chloride to form the corresponding phosphate ester. Hydrogen chloride is liberated as a by-product. Accordingly, a stoichiornetric amount of an organic base (e.g. pyridine) can be effectively used in order to chemically combine with the hydrogen chlorine so liberated.

As pointed out above, conventional scavenger additives are not and should not be used in the compositions of this invention. Among the reasons for this is that the copresence of conventional scavenger additives can be and frequently is harmful. For example, the deliberate addition of conventional organic halide scavengers to the fuels of this invention adversely affects the exhaust valve performance characteristics of the fuels. Consequently, organic halide scavengers are not deliberately added to the compositions of this invention; in other words, the fuels of this invention are essentially free of halogen. However, it should be understood that trace quantities of organic halide scavengers can be tolerated in the fuels of this invention. To illustrate, trace quantities of ethylene dibromide and ethylene dichloride (present in certain fuels of this invention by virtue of contamination through prior use of blending and storage equipment) produce no detectable adverse effect upon the performance characteristics of the fuels.

Another reason for not adding organic hailde scavengers to the fuels of this invention is that decided cost advantages are maintained.

Certain other additives can be used in the compositions of this invention. Hence, as used in this description and in the appended claims, the phrase essentially consisting of is intended to mean that the fuel compositions of this invention are devoid of conventional scavenger additives (other than trace quantities incurred through contamination) and also that any other ingredient of these compositions is selected with due regard to the principles given below.

Antioxidants can be effectively used in the fuel compositions of this invention. Particularly useful materials for this purpose are N,N-di-sec-butyl-p-phenylene diamine, p-N-butylaminophenol, 4-methyl-2,6-di-tert-butyl phenol; 2,6-di-tert-butyl phenol and 2,4-dimethyl-6-tertbutyl phenol. Good results are achieved when these antioxidants are present in the fuels of this invention in concentrations ranging from about 0.5 to about 25 pounds per 1000 barrels.

Metal deactivators can also be used to advantage in the fuel compositions of this invention. One very suitable material is N,N'-disalcylidene-1,Z-diarninopropane. Generally speaking, concentrations ranging from about 0.1 to about 3 pounds per 1000 barrels are satisfactory.

Additives imparting anti-icing and anti-stalling characteristics can also be used in the fuels of this invention. Preferred for this purpose are such materials as methanol, isopropanol, or mixtures thereof (concentrations ranging from about 0.5 to about 2 percent by volume are satisfactory; substantially neutral salts formed from primary alkyl amines and alkyl acid orthophosphates (concentrations corresponding to about 2.5 to about 25 pounds per 1000 barrels are satisfactory); and the fi-hydroxyethyl ethylene-diamine amides of oleic acid (satisfactory concentrations range from about 50 to about 200 parts per million based on the fuel). Some of these additives also confer detergency properties upon the fuels.

Among the other additives which may be employed in the fuels of this invention are dyes, top-cylinder lubricants, corrosion inhibitors, inert solvents, and alkyllead stabilizers.

Another important and advantageous use of the fuel compositions of this invention is in the operation of lightweight engines such as those fabricated from aluminum and magnesium and from alloys of these metals. Such lightweight engines have many advantages, especially the reduction which they make possible in over-all weight of vehicles in which they are used.

One problem which exists with such engines, especially the aluminum and aluminum alloy engines, is that gasolines containing prior art antiknock fluids cause considerable corrosion and wear. Surprisingly and unexpectedly the present compositions overcome these problems and the degree of wear or corrosion which occurs when they are used is substantially less than when conventional antiknock fluids are used approaches or equals that when clear gasolines containing no additives are employed in such engines.

We claim:

1. A halogen scavenger-free leaded gasoline composition of enhanced engine inductibility characteristics essentially consisting of:

gasoline; an alkyllead antiknock agent present in the gasoline in amount equivalent from about 1 to about 5 grams of elemental lead per gallon; a mixture of different fused ring aromatic hydrocarbons having boiling points at atmospheric pressure of at least about 180 C. and containing up to about 20 carbon atoms in the molecule, said mixture being present in amount equivalent to from about 5 to about 30 parts by weight per each 100 parts by weight of said agent;

and a triaryl phosphate ester in which the aryl groups are selected from the group consisting of phenyl, tolyl, and xylyl, the phosphorus content of the composition ranging from about 0.2 to about 0.6 theory based on the lead content of the composition.

2. The composition of claim 1 wherein said phosphate ester is tricresyl phosphate.

3. The composition of claim 1 wherein said alkyllead antiknock agent is selected from the group consisting of tetramethyllead, ethyl trimethyllead, diethyldimethyllead, triethylmethyllead, tetraethyllead, and mixtures thereof.

4. The composition of claim 1 wherein said gasoline contains from about 20 to about volume percent based on the whole fuel of aromatic gasoline hydrocarbons.

5. The composition of claim 1 wherein said alkyllead antiknock agent is tetraethyllead, wherein said phosphate ester is tricresyl phosphate present in amount equivalent to about 0.4 theory of phosphorus, and wherein said mixture includes methyl naphthalenes and dimethyl naphthalenes.

6. The composition of claim 1 wherein said gasoline contains from about 10 to about volume percent based on the whole fuel of aromatic gasoline hydrocarbons.

References Cited by the Examiner UNITED STATES PATENTS 1,889,474 11/1932 Gullander 44-58 2,080,681 5/1937 Wilson et al. 44-58 2,245,649 6/1941 Caprio 44-69 2,726,942 12/1955 Arkis et al. 44-56 2,897,069 7/1959 Brehm et al. 44-69 2,990,740 9/1961 Banigan 44-69 3,038,792 6/1962 Kerley et al. 44-69 FOREIGN PATENTS 448,446 6/ 1936 Great Britain. 670,526 4/ 1952 Great Britain.

DANIEL E. WYMAN, Primary Examiner. 

1. A HALOGEN SCAVENGER-FREE LEADED GASOLINE COMPOSITION OF ENHANCED ENGINE INDUCTIBILITY CHARACTERISTICS ESSENTIALLY CONSISTING OF: GASOLINE; AN ALKYLLEAD ANTIKNOCK AGENT PRESENT IN THE GASOLINE IN AMOUNT EQUIVALENT FROM ABOUT 1 TO ABOUT 5 GRAMS OF ELEMENTAL LEAD PER GALLON; A MIXTURE OF DIFFERENT FUSED RING AROMATIC HYDROCARBONS HAVING BOILING POINTS AT ATMOSPHERIC PRESSURE OF AT LEAST ABOUT 180*C. AND CONTAINING UP TO ABOUT 20 CARBON ATOMS IN THE MOLECULE, SAID MIXTURE BEING PRESENT IN AMOUNT EQUIVALENT TO FROM ABOUT 5 TO ABOUT 30 PARTS BY WEIGHT PER EACH 100 PARTS BY WEIGHT OF SAID AGENT; AND A TRIARYL PHOSPHATE ESTER IN WHICH THE ARYL GROUPS ARE SELECTED FROM THE GROUP CONSISTING OF PHENYL, TOLYL, AND XYLYL, THE PHOSPHORUS CONTENT OF THE COMPOSITION RANGING FROM ABOUT 0.2 TO ABOUT 0.6 THEORY BASED ON THE LEAD CONTENT OF THE COMPOSITON. 